Comparative Transcriptome Analysis Identifies Candidate Genes Related to Black-Spotted Pattern Formation in Spotted Scat (Scatophagus argus)

Spotted scat (Scatophagus argus) is an economically important marine aquaculture and ornamental fish species in Asia, especially in southeast China. In this study, skin transcriptomes of S. argus were obtained for three types of skin, including black-spotted skin (A), non-spotted skin (B) and caudal fin (C). A total of nine complementary DNA (cDNA) libraries were obtained by Illumina sequencing. Bioinformatics analysis revealed that 1358, 2086 and 487 genes were differentially expressed between A and B, A and C, and B and C, respectively. The results revealed that there were 134 common significantly differentially expressed genes (DEGs) and several key genes related to pigment synthesis and pigmentation, including tyrp1, mitf, pmel, slc7a2, tjp1, hsp70 and mart-1. Of these, some DEGs were associated with pigmentation-related Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways, such as tyrosine metabolism, melanogenesis, the Wnt signaling pathway and the mitogen-activated protein kinase (MAPK) signaling pathway. The results will facilitate understanding the molecular mechanisms of skin pigmentation differentiation in S. argus and provide valuable information for skin coloration, especially the formation of spotted patterns on other marine fish species.